The present invention relates to a method for improving solubility of a protein by irradiating the protein with an electron beam, the protein treated by said method and a product containing the protein treated by said method.
In general, proteins used for food and industry include water-soluble proteins and water-dispersible proteins. For utilization of the proteins, there has been demanded improvement of nutrition and functional properties such as capacities of holding water, gelating, adding viscosity, emulsifying, bubbling, adding body, solidifying, adding taste, flavoring, or adding preservability, sweetening, as well as enzyme activation.
Among conventionally used proteins, few kinds of proteins are water-soluble. A common method for dissolving the protein in water is to change acidity or basicity (pH) of a solution by using an alkali or an acid.
For dissolving a water-dispersible protein in water, the following means other than changing pH are usually employed.
As to muscle proteins such as actin and myosin contained in animal meat and fish meat, it is known that their solubility in water is improved by a salt-solubilization using sodium chloride, or solubilization with a salt having chelating ability by adding a sodium citrate or a polyphosphate such as tripolyphosphate. The process utilizing sodium chloride is applied not only to animal proteins but also to plant proteins such as wheat proteins. Further, as to milk-derived proteins such as acid casein, improvement of water solubility is realized by salification through addition of sodium hydroxide, potassium hydroxide or calcium hydroxide. Moreover, it is also known as a method for improving the solubility to decompose proteins to lower molecular proteins by using acids such as hydrochloric acid or enzymes such as protease.
As described above, functional properties of the protein such as capacities of emulsifying, thickening, holding water and gelating are extracted by improving the solubility. In order to make the best use of the functional properties, the solubility of the protein in water must be improved. However, the properties are not fully exhibited by the known methods.
Thus, it has been demanded an easily operatable and industrially inexpensive method capable of large-scale treatment for improving the water solubility of the protein without alteration and decomposition of the protein.
As a result of eager researches to solve the above-mentioned problems, the inventors of the present invention have found that irradiation of a protein with an electron beam improves the water solubility.
According to the present invention, provided is a method for improving solubility of a protein in water by irradiating the protein with an electron beam, the protein treated by said method, and a product containing the protein treated by said method.